Propeller



Sept. 8, 1925. 1,552,637

S. A. MOTHERAL PROPELLER Ori Filed Feb. 9

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El '3 D Patented Sept. 8, 1925.

UNITED STATES. "PATENT OFFICE.

SAMUEL A. MOTHERAL, OF OSSININGg N EW YORK.

PROPELLER.

Application filed February 9, 1922, Serial No. 535,288. Renewed December5, 1924.

To all whom it may concern:

Be it known that I, SAMUEL A. MOTHERAL, a citizen of the United States,residing at Greenmont, Ossining, in the county of \Vestchester and Stateof New York, have invented certain new and useful Improvements inPropellers, of which the following is a specification.

This invention relates to lifting or propulsion devices for general useon various kinds of vehicles or other purposes, with special referenceto rotary propellers adapted for co-operation with any fluid medium,such as air or water.

Generally speaking the propeller shown and described herein is designedparticularly for use in connection with flying machines or other airvehicles, and broadly considered the invention relates to the subjectmatter of my co-pending applications for flying machines filed May 8th,1919, Serial No. 295,566 and vacuum flying machines filed December 11th,1918, Serial No.

266,239, and renewed November 19th, 1921, under Serial No. 516,512.

Among the objects of this invention is to provide a propeller theefficiency of which is dependent primarily upon the rapid movement ofthe blades thereof through the medium, with a view of causing theleading edge portion of each blade to pass through the medium with theleast amount of resistance, forming in effect simply a parting orcleavage of the medium, as distinguished from the action of theconventional propeller blade which is depended upon for its efliciencyto impart a thrust to and movement of the medium in a direction parallelto the axis of the propeller. It will be borne in mind, therefore, thatfor a propeller blade to be so shaped as to cause or create a decidedthrust upon the medium, it follows that the resistance tending to retardor prevent the rotation of the propeller must be relatively enormous,whereas in my new propeller the resistance tending to retard or preventits rotation is so slight as to be hardly more than negligible.

Another object, as a corollary to the statement just made. is to providea propeller, the blade or blades of. which, being so shaped as to reduceto a minimum the resistance of the medium to rotation, will possessmaximum strength and so consequently may be constructed of suchrelatively light or thin material as to provide incidentally for maximumspeed of rotation, and still be perfectly safe and reliable.

Another 0 ject is to take advantage of and utilize what may betermed thestatic pressure of the fluid medium, causing the same to be exerted onone face or slde of the propeller blade with a force superior to thecorresponding pressure on the opposite side or face of the blade.

With the foregoing and other objects in view the invention consists inthe arrangement and combination of parts hereinafter described andclaimed, and while the invention is not restricted to the exact detailsof construction disclosed or suggested herein still for the purpose of,illustrating a practical embodiment thereof reference is had to theaccompanying drawings, in which like reference characters designate thesame parts in the several views, and in which Figure 1 is a diagramindicating an air ship equipped with my improved lifting and tractionpropellers.

Fig. 2 is a perspective View of one design of propeller having twoblades and adapted especially for high speed of rotation.

Fig. 3 is a cross section of the blade on the line 3-3 of Fig. 2.

Fig. 4 is a plan view of a disk shaped propeller provided with moreblades than two but having the fundamental characteristics above setforth.

Fig. 5 is a transverse section on the line 55 of Fig. 4.

Fig. 6 is a detail perspective view indieating a slightly modified formof high speed propeller blade.

Figs. 7 and 8 are edge and plan views respectively of a type ofpropeller designed more particularly for maximum strength.

Fig. 9 is a cross section on the line 9-9 of Fig. 8.

Fig. 10 is a cross sectional view of a further modification.

With specific reference to the construction of Figs. 2 and 3 I show forhigh speed rotation a propeller 10 having two blades-11 extending indiametrically opposite directions from a center or hub 12, which hubhowever may extend beyond the plane of the blades or not depending uponthe specific assemblage in which the propeller may be employed. The hubhowever is indicated in order to establish the axis 13 of the propelle'rand to bring forth the fact that the blades lie and move ordinarily in aplane to which said axis is perpendicular.

As shown best in Fig. 3 each blade comprises a relatively sharp leadingedge 14 midway between the forward and rearward faces 15 and 16,respectively, which are parallel to each other and consequently lie inparallel planes perpendicular to the axis aforesaid. The term forward asapplied to the face 15 will be understood as being relative insignificance and will be employed to establish the action of thepropeller blade rather than to limit the position of the propeller withrespect to any specific equipment. In other Words when the propeller isemployed for liftin and with its axis arranged vertically the face 15will be uppermost and the direction of movement of the blade will betoward the right as indicated by the arrow a, while the effectivedirection of movement of the machine will be understood as being in thedirection of the arrow 7) parallel to the axis 13.

The trailing edge portion of the blade is reduced below or back of theplane of the face 15, the same being indicated in Fig. 3 as beingbeveled from the point or line 17 at the trailing edge of the face 15 tothe point or edge 18 constituting the trailing edge of the rear face 16.While this trailing portion is indicated as beveled in a flat surface 19in Fig. 3 it "will be understood that the reduction may be otherwiseformed, such as concave as shown at 19 in Fig. 5 or at 19 in Fig. 6.From the point 20 directly opposite the point 17 there is provided afiat trailing face portion constituting a continuation of said rearwardface 16, and so that portion of said rearward face between the points 18and 2Q constitutes or determines the extent and area of the rearwardface 16 in excess of the effective flat portion of the forward face 15.The leading edge portion between the cutting edge 14 and the twosubstantially fiat surfaces 15 and 16 may be variously proportioned orshaped according to the specifications of the machine as to speed ofrotation and lifting power. As shown, however, in Figs. 3, 4, and 6 thesurfaces 21 of the blade adjacent to the leading edge 14 are indicatedas practicallyv flat and meeting at the leading edge in an acute. angle.In all cases however the forward and rearward faces of the leading edgeportion of the blade are symmetrically shaped with respect to the medianplane of the blade which coincides with the leading edge 14. It followstherefore that when the blade is moved in the direction of the arrow aand said median plane thereof, there is little or no tendency for eitherthe forward or the rearward face thereof to drive the medium eitherforward or rearward, the medium rather being simply sepa; rated or splitby the cutting or leading edge portion of the blade, thereby maintainingthe normal static pressure of the medium constant on a unit of area onboth the forward and rearward surfaces 15 and 16. Such pressure beingexerted on the facet) directly toward-the bladeis neutralized by thepressure on all of that portion of the rearward face back to the point20, respecting the surface equal in extent to the forward face 15.

As a result of rapid movement of the blade in the direction of the arrow(1 a vacuum tends to be formed and is formed to a greater or less degreeaccording to the speed of rotation of the propeller adjacent to thereduced trailing portion of the blade or next to the surface 19.Consequently the rearward pressure of the medium on the upper or forwardface of the blade, considered now as a whole all the way from the point14 to the point 18, will be reduced below the pressure on the rearwardface of the blade, considered between the two extreme points 14 and 18,in proportion to the degree of vacuum formed adjacent to the surface 19.In other words, theoretically if a perfect vacuum be produced betweenthe points 17 and 18 along the surface 19, the static pressure of themedium, being constant along the flat surface 16, will all be exertedwithout opposition with respect to the surface or area between thepoints 18 and 20, tending to push or lift the propeller in the directionof the arrow 6.

The leading edge portion of the blade may be termed a divider forsplitting or cleaving the medium, the sides of the divider being ofequal width and disposed at inclinations of equal angle; with respect tothe median plane of the blade. As a result of extensive experiments ithas been proved that thistype of blade does possess phenomenal liftingand propelling power based upon the theory just described, and that thepower remains constant irrespective of the direction or position of theaxis of the propeller. That is to say, the blade has alifting power,measured in terms of pounds per horsepower, exactly equal to itshorizontal thrust when rearranged for traction purposes, the prime moverand other conditions remaining unchanged.

It will be now understood that a propeller such as indicated in Figs. 2and 3 and whose blades are relatively thin and glide with but slightresistance through the medium is cap-able not only of high speedrotation but is subject to the least likelihood of breaka e ordistortion.

In Flg. 4 I indicate a disk shaped propeller having a hub 12 and anysuitable disk or web 21 designed for maximum strength and the leastamount of resistance against rotation. At the periphery 22 of this diskare formed or fastened in any suitable manner a series'ofblades 11,shown as six in number, but each having as shown a maximum thicknessequal to the thickness of the disk. Hence this construction whileproducing slight resistance to rotation will afford maximum lifting ortraction properties due to the increasedarea of the combined rearwardsurfaces 16 over the forward surfaces The principle of operation in allforms of'my propeller shown herein remains the same. r

In Fig. 6 the forward face 15 and rearward face16" differ from the formin Fig. 3, except as above noted, only in providing slight concavitiesalong these portions which were described above as being flat andparallel. The efliciency of this form of blade lies in the fiat trailingportion of the rearward face as in the other forms of the dev1ce.

In Figs. 7, 8, and 9 I provide a propeller of the two blade type,diametrically oppo: sitely arranged asin Fig. 2, but each blade 11 ofwhich is materially strengthened ad jacent to the hub. In other wordsthe construction is of considerable fullness adjacent to the hub butwith a taper outward toward the ends of the blades. edge 14, however,following the novel principle of construction above indicated, is assharp as the massiveness of the blade will permit and is located in themedian plane or midway between the remote portions or edges of theforward and rearward faces 15 and 16 respectively. As in the other 1forms there is yet observed on the rearward face of these blades aflatportion between the points or lines 18 and 20 which is essentiallyperpendicular to the axis except as may be incident to the aforesaid.outward taper of the blade as a whole. Opposite this flat lifting orpropelling surface is located the surface 19.

The air ship indicated in Fig. 1 comprises a body 23 having an upperdeck 24 for pas sengers and light baggage. and a lower deck 25 for heavybaggage, freight, machinery, fuel, or the like. For the "lifting of theship I provide a plurality of propellers or lifting elements 10 mountedon vertical axes and adapted to be rotated bv any suitable prime moversindicated at M. Attached to the shafts 13, or other shafts below thedeck 25, are other propeller elements 10' designed for the control orneutralization of the effect of the lifting propellers 10. While thisair ship is' designed for a vertical rise or descent within any spacethat will receive its length and width, and independent of traction orsteering mechanism, it also will be capable of remaining stationary atany desired elevation in the atmosphere by virtue of the lifting abilityof the new type of propeller herein described. At the front end of thebody 23 are arranged one or more The leading which because of thepeculiar merit of the propelling elements will propel the machineforward at high speed while the propellers 10 or some of them continuein operation t9 sustain theair ship at its desired elevation. One ormore steering propellers 10 of any suitable'type are provided upon atransverse horizontal axis at the rear end of the body through which theship is steered laterally...

Fig. 10 indicates a practical form 10 of my improvement whichillustrates that While the leading edge 14 is essentially midway betweenthe extreme forward and extreme rearward parts 17 and 18 of the blade,it is not necessary in all cases for the surfaces 15 and 16 leading fromsaid leading edge forms of the invention first described.

I claim:

1. In a flying machine, the combination with a body and power meanstherein, of a lifting member for the body serving to lift the'samebodily and operated from said power means,said lifting member comprisinga propeller including a substantially flat blade movable at high speedaround an axis parallel to the direction of lifting movement andcarrying at its leading edge a divider serving to split the air andthereby produce a rarefaction of the air and a corresponding reductionof downward air pressure over the upper surface thereof, while thecondition and upward pressure of the air beneath the blade remains essentially constant, said divider having sidesof equal width and disposed atinclinations of equal angle with respect to the median plane of theblade.

2. A power element for flying machines or other vehicles comprising ablade having flat spaced parallel longer and shorter rearward andforward surfaces respectively, a leading edge connecting said surfaces,the crest of the leading edge being substantially midway betweensaidsurfaces, said shorter surface lying directly forward of the lead- Iing edge of the shorter surface, and the trailing edges of both surfacesbeing connected by a surface offset rearward from the plane of theshorter surface toward the plane of the longer surface.

, 4. A ropeller blade as set forth in claim 3 in which the extendedtrailing portion of the longer surface is fiat and lies within the planeof its movement.

5. A ropeller blade as set forth in claim 3 in which the blade isprovided witha leading dividing edge midway between the two parallelsurfaces and having ad acent surfaces of equal symmetrical form leadingfrom said leading edge into the parallel surfaces.

6. The herein described propeller comprisin a blade for movement at highspeed aroun its axis, said blade comprising a leading edge midwaybetween the foremost and rearmost parts of the blade and being united tosaid foremost and, rearmost parts by symmetrically formed surfaces, saidsurfaces and the leading edge connecting them constituting a divider forparting the medium equally with a minimum resistance, and said rearmostportion of the blade being included in an extension leading to thetrailing edge of the blade and lying in the path of movement of saidrearmost portion While the forward side of the blade is reduced for theformation of a vacuum between the trailing edge of the foremost ortionof the blade and the trailing edge a oreIsaid.

7. A propeller blade for movement at high speed around its axiscomprising aleading edge midway between the foremost and rearmost partsof the blade and being united to said foremost and rearmost parts bysurfaces constituting with the leading edge a divider for parting themedium equally with a minimum resistance, and said rearmost portion ofthe blade being included in a trailing extension more remote from theleading edge than the trailing part of the foremost portion of theblade, whereby a Vacuum is formed on the forward side of the bladeadjacent to the trailing edge portion thereof and opposite saidextension of the rearmost surface aforesaid.

In testimony whereof I aflix my signature.

SAMUEL A. MOTHERAL.

